A sidecar XMP file is a small text file that sits next to a raw photo and holds the edit settings and metadata for that image. Lightroom keeps your edits in its catalog first, and writes them to XMP files only when you ask or when a setting tells it to.
Why Edits Live Outside the Raw File
Editing a raw photo in Lightroom never changes the original file. Instead, the program records a list of instructions, such as exposure, white balance and crop, and applies them each time it shows the image. That list has to be saved somewhere, and there are two places: the catalog and the sidecar file.
A sidecar file shares the name of the raw file but ends in .xmp. For example, a raw file named IMG_0042 would sit beside IMG_0042.xmp. Scores, keywords and color labels can be stored there too.
Where Lightroom Stores Your Edits
- In Lightroom Classic, the catalog file is the main record of your edits and metadata.
- XMP data is an extra copy, written on request, that travels with the photo.
- For DNG, JPEG and TIFF files, the information can be written inside the file itself, so no separate sidecar is needed.
- Other Adobe tools, such as Bridge and Camera Raw, read XMP sidecars directly when they open a raw file.
How to Write XMP Files in Lightroom Classic
- Open the Catalog Settings and go to the Metadata tab.
- Tick the option to automatically write changes into XMP if you want every edit saved beside the file. This can slow things down on large libraries.
- Or, to save on demand, select your photos and use Metadata, then Save Metadata to File.
- Check your folder in a file browser. A new .xmp file should appear next to each raw file.
Keeping Sidecars Safe
The biggest trap is moving files. If you move or copy a raw file in a file browser and leave the .xmp behind, the edits do not follow it. Always move the pair together, or move files inside Lightroom so it handles the sidecar for you.
For backups, copy the catalog and the photo folders, including any .xmp files. If you plan to open the same raw files in another editor, write the XMP data first. Other programs may read some of it, but support for specific edit settings varies, so confirm on the software maker’s page.
| File type | Where edit data goes |
|---|---|
| Raw (maker format) | Catalog, plus optional .xmp sidecar |
| DNG | Catalog, plus inside the file when saved |
| JPEG and TIFF | Catalog, plus inside the file when saved |
FAQ
If I delete the XMP file, do I lose my edits?
Not if the catalog still has them. The catalog is the main record in Lightroom Classic. But if you open the folder in another program or on another computer, the edits will be missing without the sidecar.
Why do I not see XMP files next to my photos?
Lightroom only writes them when automatic writing is on or you save metadata manually. Photos in JPEG, TIFF or DNG format store the data inside the file instead.
The Short Version
Sidecar XMP files are small companion files that carry your edit settings and metadata beside a raw photo. Lightroom Classic stores edits in its catalog and writes XMP on request. Keep each sidecar with its raw file and include both in your backups.
